Heat Exchanger Coating Anti-Corrosion Water-Based Paint The manufacturer explains the defects of water-based anti-rust coatings and how to prevent them.

　　A Brief Discussion on Preventing and Controlling Common Defects in Water-Based Rust-Proof Coatings

　　Common Defects in Water-Based Rust-Proof Coatings

　　The freshly packaged paint has unclear advantages and disadvantages—its true qualities only become apparent once the can or bucket is opened, revealing its appearance and stability. At this stage, common defects may include water floating on top, solidification at the bottom, foam forming on the surface, or even signs of spoilage and mildew. Moreover, the final performance of the paint can only be assessed after actual application during construction. In this phase, issues like sagging, reduced coverage in certain areas, air bubbles or pinholes in the dried film, unevenness across the surface, and a lack of proper gloss and fullness in the outer coating often emerge. Over time, if the paint and application quality are subpar, more serious problems may arise, such as cracking, peeling, blistering, or even rust formation. Notably, water-based paints, due to their inherent limitations, tend to exhibit more defects compared to solvent-based alternatives.

　　Based on our experience from R&D practices, we have implemented the following measures to prevent and address the identified defects.

　　According to the prescription for prevention and control, the key is to reduce the surface tension of the coating. The primary difference between waterborne and solvent-based coatings lies in the dispersing and diluting medium used, which directly affects their surface tensions. Notably, waterborne coatings tend to have more issues compared to solvent-based ones. Therefore, when formulating water-based anti-corrosion coatings—whether high-quality or lower-grade—it’s essential to prioritize reducing the coating’s surface tension and enhancing its adhesion to the substrate. To achieve this, first, carefully select a substrate wetting agent that requires minimal dosage yet delivers superior performance, ensuring optimal compatibility with the coating system. Additionally, incorporate appropriate additives tailored to address specific needs. Second, consider adding an adhesion promoter specifically designed for waterborne coatings. Among these, silane coupling agents stand out due to their exceptional fluidity, allowing them to effortlessly migrate to the organic/inorganic interface. Meanwhile, titanium ester coupling agents not only effectively wet the substrate but also help suppress foam formation and improve film flow and leveling. Third, using low-surface-tension leveling agents can significantly enhance the base coat’s ability to spread across the substrate, increasing the number of adhesion points while simultaneously promoting smoother, defect-free coating surfaces. Finally, supplement the formulation with a blend of glycol ether solvents that vary in evaporation rates. This approach not only aids in achieving a more uniform and durable film formation on the substrate but also helps further reduce the coating’s surface tension. However, it’s crucial to balance the addition levels with drying conditions and application processes to ensure optimal results. Ultimately, these additives work synergistically to minimize the coating’s surface tension and maximize adhesion, delivering superior performance in both protective and aesthetic applications.

　　By appropriately implementing the measures outlined above, we addressed defects such as peeling, blistering, and inconsistent adhesion in both self-drying primers and baked coatings. Additionally, we tackled issues like uneven, rough, or insufficiently full coating surfaces on exterior applications, as well as the limited lifespan of coating layers—by carefully selecting and adjusting the proportions of suitable resins.

　　To address common issues in water-based coatings—such as roughness, excessive foaming, shrinkage cavities, poor appearance, and uneven film thickness—a "light-touch" approach using specialized additives has been developed. The "Four-Two" method involves employing more than two types of wetting and dispersing agents, combining two or more foam-reducing and defoaming agents, utilizing two or more film-forming co-solvents, and incorporating two or more rheology modifiers. Specifically, the use of over two wetting and dispersing agents ensures that the pigment slurry is finely ground, enabling the coating film to achieve optimal adhesion, smoothness, gloss, and resistance to contamination.